Combination locks have, of course, achieved considerable commercial success, but attempts to manufacture and market relatively inexpensive locks have been quite different largely because very inexpensive locks are fairly simple to pick. While the present lock is exemplified as an aftermarket combination lock for pistol cases, the lock has other low costs applications, and hence, the prior art is equally as broad.
A preliminary patentability search resulted in the following collection of U.S. Pat. Nos.: Enholm, 428,387; Battershell, 1,733,772; Legat, 1,898,974; Ponder, 2,740,530; Nemsky, 3,155,230; Esquibel, et al., 3,514,981; Feinberg, 3,597,945; Pedro, 3,865,166; Jones, Re. 30,139; Ippolito, et al., 4,187,703; Gordon, 4,463,847; Terada, et al., 5,081,855; Jarboe, 5,125,661; and Blanchard, 5,322,200.
The Ippolito, et al., U.S. Pat. No. 4,187,703, shows a locking system applied to an envelope defined by a pair of spaced plates, holding a numismatic coin. The Ippolito device has a slide plate 14 with cross slots 16 transversely positioned away from a central longitudinal slot 18. The transversely movable slides are all identical and can be positioned either in a right-hand or left-hand orientation as seen in FIG. 9. This arrangement, however, produces only two positions for each switch and, therefore, yields few combinations.
The Jarboe, U.S. Pat. No. 5,125,661, discloses a plunger-type locking mechanism, but there is really no logic in the lock combination because if all the plungers are depressed, the plunger 19 can be removed regardless of the position of blocks 35. Thus, it is not really a true combination lock at all.
The Esquibel, et al., U.S. Pat. No. 3,514,981, discloses a plunger-type locking mechanism for a box wherein a locking bar 14 is held or released by a plurality of slide bars 13 that have second slots 30 all positioned the same distance from the inner ends of the bars, and first slots 29 positioned in varying locations to correspond to one of the indicia on area 33 of the projecting ends of the bars 13. When the bars are slid to the appropriate indicia, the slots 29 permit the release of bars 14. The Esquibel, et al. lock has a total of only 48 combinations possible with five bars 13.
It is a primary object of the present invention to ameliorate the problems noted in the prior art above and provide a low cost combination lock that is considerably more tamper-proof than prior art constructions while at the same time having a greater number of possible combinations.